Summary

نقل ذرة الراديكالي بلمرة Functionalized الفينيل مونمرات عن طريق Perylene بمثابة حفاز ضوئي ضوء مرئي

Published: April 22, 2016
doi:

Summary

A method for the atom transfer radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst is described.

Abstract

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism.

Introduction

The synthesis of technologically advanced polymers requires precise control over polymer molecular weight, dispersity (Ð), composition, and architecture.1,2 Controlled radical polymerizations (CRPs)3-8 have revolutionized the synthesis of well-defined polymers, with atom transfer radical polymerization (ATRP) being the most used CRP, largely due to operational simplicity and synthetic versatility.9-14 The crux of ATRP is the ability to reversibly deactivate the polymerization, controlling the equilibrium between a propagating radical and a dormant species. Enforcing a low concentration of active radicals greatly minimizes bimolecular termination pathways and allows for the synthesis of well-defined polymers.

Traditional ATRP relies on a transition metal catalyst to mediate this equilibrium.3 These metal catalysts contaminate the polymer product and impede implementation in biomedical or electronic applications while also raising environmental concerns. Although significant strides have been made to reduce the catalyst concentration to ppm levels, these methodologies require more demanding experimental conditions and metal contamination is still not entirely eliminated.15,16

Reversible addition-fragmentation transfer17,18 and nitroxide-mediated polymerizations19,20 are CRPs that do not require metal catalysts, although they have been used less often than ATRP.3 Recently, reversible chain-transfer21 and reversible complexation22,23 variants of ATRP that can use organic catalysts were reported. However, these methodologies require the use of alkyl iodide initiators and are not effective with the alkyl bromides commonly employed in ATRP. A highly desirable CRP would match the performance, feasibility, and robustness of traditional ATRP while being catalyzed by an organic catalyst under mild conditions.

Here, we describe a methodology for the radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst. Through optimization of parameters such as stoichiometry, concentration, time, and light flux, the molecular weight of the polymers can be controlled.24, 25 Similar methodologies have been recently introduced using phenothiazine derivatives as photocatalysts for metal-free ATRP.26, 27 Because researchers in the field of polymerization catalysis are constantly developing new catalytic systems, the ability to compare catalyst performance across a number of metrics is vital. This ability to make comparisons relies heavily upon procedural consistency and clarity on the part of the researchers performing the experiments. As such, it is our goal that this video will be used to help precisely communicate the methods by which these polymers are synthesized and characterized.

Protocol

تنبيه: كثير من المواد الكيميائية المستخدمة في هذا البروتوكول هي المواد الخطرة. الرجوع إلى صحيفتي بيانات سلامة المواد (MSDS) واستخدام معدات الوقاية الشخصية المناسبة (PPE) عند العمل مع هذه المواد. 1. تنقية، إعداد وتخزين الكواشف <ol style=";t…

Representative Results

ويبين الجدول 1 مجموعة من النتائج البلمرة تحقيقها من خلال هذه الطريقة. وتشير هذه البيانات إلى أن perylene قادر على القيام بدور حفاز ضوئي للبلمرة عدد من مونومرات الفينيل functionalized. لمونومر محددة، وتعديل أي عدد من المعلمات رد فعل مثل المذيبات، ر?…

Discussion

على الرغم من أن البروتوكول يوضح مثال محدد من هذه التقنية البلمرة، والخيارات المتاحة للباحث أداء هذا رد فعل واسعة جدا. يمكن إجراء التعديلات على عدد من النقاط في جميع أنحاء بروتوكول للسماح الاستفادة المثلى من كل ما photoredox خاص يتم تنفيذ ATRP. كما أحادية جديدة، المبادرين، و…

Divulgations

The authors have nothing to disclose.

Acknowledgements

The authors would like to acknowledge the University of Colorado Boulder for its support of this work.

Materials

perylene, min 98.0% TCI America TCP0078-025G purify by sublimation
N,N-dimethylformamide VWR EM-DX1726-1 Omnisolv
methyl methacrylate, 99% VWR 200000-678 distilled prior to use, stored in refrigerator
ethyl α-bromophenyl acetate  Aldrich 554065 distilled prior to use stored in refrigerator
butylated hydroxytoluene  Aldrich W218405
Chloroform-D Cambridge Isotope Labs DLM-7-100
tetrahydrofuran VWR EM-TX0279-1 Omnisolv
methanol VWR BDH1135
dichloromethane VWR EM-DX0831-1 Omnisolv
styrene, 99% VWR AAAA18481-0F distilled prior to use, stored in refrigerator
glass scintillation vial, 20 mL VWR 66022-065
screw top vial, 2 mL Agilent 5182-0715
septum cap for screw top vial Agilent 5182-0717
heavy wall pressure vessel, 100 mL Synthware P160005 
syringe, 1 mL norm-ject VWR 89174-491
NMR tube New Era NE-UL5-7'
nylon syringe filter, 0.45 um VWR 28143-240
glovebox Mbraun LABstar
solvent purification system Mbraun MB-SPS-800
stirplate IKA 3582401
light-emitting diodes Creative Lighting Solutions CL-FRS1210-5M-12V-WH 2x 12-inch strips of 5500 K white LEDs were used for illumination
12V DC power supply for LEDs Creative Lighting Solutions CL-PS16001-40W
high performance liquid chromatograph  Agilent G1310B, G1322A, G1329B, G1316A
gel permeation size-exclusion columns Agilent PL1110-6500
multi-angle light scattering detector Wyatt WTREOS
differential refractometer Wyatt WTREX

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Citer Cet Article
Theriot, J. C., Ryan, M. D., French, T. A., Pearson, R. M., Miyake, G. M. Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst. J. Vis. Exp. (110), e53571, doi:10.3791/53571 (2016).

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